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POdisplaying a large amount of formatted text in Python
 

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  1. POdisplaying a large amount of formatted text in Python
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    <p>I have two large identical-sized files. One is ASCII plain text, and the other is a colour-coded overlay, one byte per text character in the corresponding file.</p> <p>These files can be large - upto 2.5 MB; possibly substantially more, perhaps over 100MB later.</p> <p>I want to display the text is a scrollable text viewer, using the second file as the overlay. Looking something like this:</p> <p><a href="http://img713.imageshack.us/img713/2584/statsviewer01d.png">Tkinter Text window with tagged text for colours http://img713.imageshack.us/img713/2584/statsviewer01d.png</a></p> <p>So I made a simple tkinter Text widget window in Python with scrollbar and such.</p> <p>My code looks like this:</p> <pre><code>hottest = 0 for heat in heatmap: hottest = max(hottest,ord(heat)) hottest += 1 for heat in xrange(0,hottest): factor = int((float(heat)/float(hottest))*100.0) # an observation; tkinter seems to normalise custom colours # to nearest in it's palette, which means I can't use custom # gradients of red; if anyone knows how to use subtle custom colours? bgcolour = "gray%d" % (100-factor) fgcolour = "gray%d" % factor text.tag_config("n%d"%heat,background=bgcolour,foreground=fgcolour) text.insert("1.0",f.read()) ofs = 0 for heat in heatmap: if 0 != ord(heat): coord_start = "1.0 + %d chars"%ofs coord_stop = "1.0 + %d chars"%(ofs+1) text.tag_add("n%d"%ord(heat),coord_start,coord_stop) ofs += 1 text.config(state=DISABLED) text.focus() </code></pre> <p>However, I run into horrid performance problems:</p> <ol> <li><p>loading the text</p> <ul> <li>if I simply use textwidget.text = textfile.read() it loads instantly, even for the large file; but then the problem is colour-coding it. <em>(see code above)</em>. To add the tags, one character at a time, it seems I force it to take a <a href="http://www.joelonsoftware.com/articles/fog0000000319.html">painter algorithm</a>; by the time the file is about 300KB in size, I give up waiting for it to load</li> <li>if I read the next character from the textfile and the colourfile, and append a properly tagged character, it takes forever; a file bigger than about 200KB and I give up waiting for it to load</li> </ul></li> <li><p>Scrolling. If this much formatting visible in the current window, it goes very slowly</p></li> </ol> <p>If I was approaching this problem in, say, Dephi or wxWidgets or whatever, I'd have a custom-drawn control.</p> <p>What's the most straightforward way in Python and Tkinter?</p>
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    1. COconsider stopping using Tkinter. I don't know if what you ask is possible, but Tkinter has lots of limitations and is generally overcomplex to work with.
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      1. USnosklo
    2. CO@nosklo: If you have a suggested alternative, please post that as an answer so we can upvote it.
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      1. USS.Lott
    3. CO@nosklo: what are the alternatives? Portable, free, well documented, easy, ...?
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